thrift: avoid auto in function argument declaration
thrift: avoid auto in function argument declaration

'auto' in a non-lambda function argument is not legal C++, and is hard
to read besides.  Replace with the right type.

scylladb/scylla,avikivity/scylla,duarten/scylla,scylladb/scylla,scylladb/scylla,duarten/scylla,avikivity/scylla,avikivity/scylla,scylladb/scylla,duarten/scylla